The project will investigate and perfect analytical tools for the description and prediction of growth in children. These procedures, which have been successfully tested in prototype, describe serial measurements over all or part of the growth cycle in terms of a compact model well suited to the study of genetic and environmental determinants of development. They also support an accurate and flexible system for the clinical evaluation of current growth status and the prediction of future growth as part of the preparation for the treatment of developmental disorders. The project will complement this structural approach to the analysis of serial measurements with a nonstructural description of more detailed variation within the main phases of growth in early, middle and late childhood. Our preliminary studies by this method already indicate the presence of "miniphases" of growth acceleration and deceleration during the years from four to adolescence. Further study, using the growth records for parent and offspring in two- and three-generation families available in the database of the Fels Longitudinal Study, will enable us to evaluate indications that these short-range growth phases have a heritable basis. The analytical tools developed in the project will be implemented in computerized form suitable for research and clinical use. They will include a procedure adapted to monitoring changes in the velocity and extent of growth during and following treatment interventions.